Just For Men Mustache & Beard #Darkest BrownJust For Men Mustache & Beard hair color hides shades of gray hair and brings out the best in your facial hair. Facial hair looks fuller, more even, and well-groomed as you get rid of the scraggly look of gray facial hairs. The fast and easy beard hair dye works in 5 minutes – your gray hair will be gone until it grows back.